Light-sensitive color photographic materials for photographing in general are required to obtain preferable images in a broad exposure range. That is, it is desired to have light-sensitive color photographic materials having a broad latitude of exposure. In the prior art, there have been known such methods as mentioned below as the techniques for such broadening of latitude.
One method comprises broadening the crystal size distribution of silver halide crystals by such a method as mixing crystals with different crystal sizes, namely large crystals and small crystals, etc. corresponding to the desired latitude. It is also known to attempt broadening of latitude by separating silver halide emulsion layers having respective color sensitivities into a high sensitivity layer and a low sensitivity layer, as disclosed in Japanese Provisional Patent Publication No. 42355/1974, U.S. Pat. No. 3,843,469, etc. Further, there is also known the method in which broadening of latitude is attempted by reducing the silver halide content in a light-sensitive material.
However, a number of problems are known to be involved in any of the light-sensitive silver halide materials using the above methods, such as worsening of graininess and development stability, etc.
Also, in case of a light-sensitive color photographic material having a negative type silver halide emulsion layer of softer gradation, there is the method to attempt broadening of latitude by use of a multiequivalent coupler to reduce utilization efficiency of silver halide, as disclosed in Japanese Provisional Patent Publication No. 135841/1981. However, this method requires an increased amount of silver halide, thus involving a great problem from the standpoint of silver saving.
Further, it is also known in the art that latitude can be broadened by applying a compound capable of releasing a development inhibitor at the time of developing such as an inhibitor releasing type developer, an inhibitor releasing type coupler (DIR coupler) or an inhibitor releasing type compound (DIR substance) to a light-sensitive material. However, these compounds not only broaden latitude but also may sometimes cause sensitivity reduction during storage, whereby the extent of broadening of latitude is naturally limited. Also, while it is possible to control the latitude by increasing the iodine content in a silver halide emulsion, increase of the iodine content in a silver halide results disadvantageously in lowering of emulsion sensitivity.
In the prior art, a polydispersed emulsion is employed in a silver halide emulsion as the emulsion. This is because use of a monodispersed silver halide emulsion, while it enables uniform chemical ripening of respective crystals on account of a narrow crystal size distribution of silver halide and is also advantageous in aspect of crystal size-sensitivity, involves the drawback that the gradation becomes hard and the latitude of exposure is narrowed. Accordingly, although a polydispersed silver halide emulsion is employed in any of the methods as described above, none of these methods are sufficient in imparting broad latitude and providing good sensitivity and development stability.
An object of this invention is to provide a light-sensitive material improved in reducing the drawbacks as described above possessed by the light-sensitive color photographic materials of the prior art, particularly a light-sensitive silver halide color photographic material which, while maintaining a high sensitivity characteristic of a monodispersed emulsion, has a broad latitude of exposure and is also excellent in gradation characteristic.
Another object of this invention is to provide a light-sensitive silver halide color photographic material having a stable performance during developing treatment in addition to the above performances.